The manufacture of articles of plastic materials by molding is expanding greatly, due to the relatively low cost, high strength to weight and simplicity of manufacture of articles of even the most complex contours necessary for a variety of end uses, and high speed of production (such plastic articles being usually plurally formed at each molding cycle). Molding machines accurately and reliably produce such articles, at each molding cycle, to precisely the contours of the mold cavity, which, in turn, are predetermined and preformed to produce the exact contours of articles desired. Such molding machines operate on sequential cycles, materials being fed into the mold cavities and heated under pressure and cooled, and the articles ejected--all under precisely sensed, sequenced and controlled time, temperature, pressure, heating, cooling, molding, ejecting and mold opening, article ejecting and mold closing procedures--all cycled, timed and pre-programmed by instrumentation and controls.
All of the just mentioned factors and the various forms of molding apparatus and molding procedures such as injection, extrusion, are old and well known to those skilled in the art--cf. "Tool Engineers Handbook" First Edition (1949) ASTE Handbook Committee, pages 392-399 showing and explaining forms of molding procedures and machines well known in this art; page 398 shows, "FIGS. 21-19--Sectional View illustrating general methods employed in injection molding--. pages 397, 399 describe sequences of operations including the heating, cooling steps. Pages 397, 398 describe sequences of the molding cycles, including heating mediums, heat sensing thermocouples, movable and stationary parts of molds, mold cooling channels, means including sprues and runners feeding plastic granules into the molds, guide pins aligning the molds in their opening and closing operations and sequences.
The contours of such plastic articles frequently include angular and other irregular portions which are difficult to form except by molding. While plastic articles may be precisely accurately molded, it is desirable to apply surface decorations to such plastic articles, for relieving the solid color appearance thereof and in order to simulate various surface and external esthetic appearances and effects. Such decorating would enhance the esthetic appearance and protect the surfaces of such articles. Surface decorating of plastic articles has however proven difficult; attempts to impress decorating surfaces on plastic articles may stress and strain them and necessitated special, costly and unreliable additional handling and completing steps, adding greatly to the cost of and time required for production thereof.
The foregoing and other problems encounted in contemplated surface decoration of plastic articles are overcome by the method and process of the present invention, which enables plastic articles to have any of an infinite variety of surface decorations desired, pleasing to the eye and to the sense of touch, formed unitarily with and during the molding of the articles, without stress or strain. Such decorations are, pursuant to the invention, applied to the articles automatically, within the mold and in the molding cycle. As the plastic material flows into and fills the mold under heat and pressure, forming the plastic article, the surface decoration preselected therefor is simultaneously automatically bonded to and forms an integral part of the article. Thus, pursuant to the present invention, at the conclusion of the molding cycle, and without any further step being required, when the mold is opened and the molded article is removed, it will have been formed, with the pre-selected surface decoration in-mold formed thereon, achieving the decorated appearance of the article.
Further advantages of the procedure of the invention include: permanent interfacial adherence, integrally achieved in-mold on the substrate as molded and heat activated. The appearance of woodgrain and other decorating effects on plastic parts of various configurations, contours, shapes and angles may be readily and accurately achieved; this is not achievable under conventional procedures. Pre-selected surfaces of injected molded parts may be decorated by selective alignment and positioning of the in-mold decorating tape relative thereto. The decoration tape pursuant to the procedure of the invention, automatically conforms to and combines with the specific three-dimensional contours of the plastic articles, as molded.